Summary

Electrical and clinical manifestations of seizures that arise from one portion of the brain. May evolve to bilateral tonic-clonic seizures.

Underlying structural brain abnormalities are known to cause a localised epileptiform focus, but idiopathic cases may occur.

History taking is the most important aspect of diagnosis. Supportive tests, although helpful, need not be abnormal for a diagnosis of focal seizures.

Monotherapy with antiepileptic medication is the preferred treatment. When polytherapy is required, this should be approached rationally, by considering the combination of different mechanisms of action and different adverse-event profiles.

Patients with 2 failed monotherapy trials followed by a failed trial of polytherapy are considered to have refractory focal seizures and should be assessed for the possibility of resective epilepsy surgery.

Definition

Focal (or partial) seizures refer to the electrical and clinical manifestations of seizures that arise from one portion of the brain. The electroencephalogram (EEG) typically indicates a localised discharge over the area of onset. Focal seizures most commonly arise from the temporal lobe. Simple partial seizures are those in which consciousness is preserved. New terminology suggests that these should now be called 'focal aware' seizures. Complex partial seizures include memory loss for the clinical event and impaired responsiveness at the time of the event. New terminology suggests that these should now be called 'focal impaired awareness' seizures. Focal seizures may evolve into secondary generalised seizures. The clinical manifestations of a particular seizure depend on the portion of the brain that is activated.
[1]Fisher RS, Cross JH, French JA, et al. Operational classification of seizure types by the International League Against Epilepsy: position paper of the ILAE Commission for Classification and Terminology. Epilepsia. 2017;58:522-530.
http://onlinelibrary.wiley.com/doi/10.1111/epi.13670/full
http://www.ncbi.nlm.nih.gov/pubmed/28276060?tool=bestpractice.com

In 2009, a task force supported by the International League Against Epilepsy (ILAE) issued a report revising the system of terminology and classification used for the description of individual seizures and epilepsy syndromes.
[2]Berg AT, Berkovic SF, Brodie MJ, et al. Revised terminology and concepts for organization of seizures and epilepsies: report of the ILAE Commission on Classification and Terminology, 2005-2009. Epilepsia. 2010;51:676-685.
http://www.ncbi.nlm.nih.gov/pubmed/20196795?tool=bestpractice.com
The clinical definition of epilepsy was revised in 2014 to include any of the following conditions: 1) at least two unprovoked seizures occurring >24 hours apart; 2) one unprovoked seizure and a probability of further seizures similar to the general recurrence risk (at least 60%) after two unprovoked seizures, occurring over the next 10 years; 3) diagnosis of an epilepsy syndrome.
[1]Fisher RS, Cross JH, French JA, et al. Operational classification of seizure types by the International League Against Epilepsy: position paper of the ILAE Commission for Classification and Terminology. Epilepsia. 2017;58:522-530.
http://onlinelibrary.wiley.com/doi/10.1111/epi.13670/full
http://www.ncbi.nlm.nih.gov/pubmed/28276060?tool=bestpractice.com
[3]Fisher RS, Acevedo C, Arzimanoglou A, et al. ILAE official report: a practical clinical definition of epilepsy. Epilepsia. 2014;55:475-482.
http://onlinelibrary.wiley.com/doi/10.1111/epi.12550/full
http://www.ncbi.nlm.nih.gov/pubmed/24730690?tool=bestpractice.com

Disclosures

At the time of review, EB declared that between 2004 and 2009, he received speaking honoraria from UCB Pharma, Novartis, Abbott Laboratories, GlaxoSmithKline, and Pfizer. He received consulting fees from UCB Pharma, Genzyme, and Spherics, and research funding from UCB Pharma. Unfortunately, we have since been made aware that EB is deceased.